验证码

odliken • • Java
内容纲要

验证码生成流程

页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="" method="post">
        验证码:<input type="text" name="checkcode"/>
        <img id="codeImg" onclick="changeImg()" src="${pageContext.request.contextPath }/CheckImgServlet"><br/>
        <input type="submit" value="提交">
    </form>
</body>
</html>

java代码

简单版

@WebServlet("/CheckImgServlet1")
public class CheckImgServlet1 extends HttpServlet {
    private static final long serialVersionUID = 1L;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width = 120;
        int height = 30;
        // 步骤一:在内存中生成一张图片
        BufferedImage bufferedImage = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        // 步骤二:操作该图片,设置背景色及绘制边框
        Graphics graphics = bufferedImage.getGraphics();
        // 设置背景色
        graphics.setColor(Color.YELLOW);
        graphics.fillRect(0, 0, width, height);
        // 绘制边框
        graphics.setColor(Color.BLUE);
        graphics.drawRect(0, 0, width-1, height-1);
        // 步骤三:生成随机的四个字母或数字,写入到图片中
        Graphics2D g2d = (Graphics2D)graphics;
        g2d.setColor(Color.BLACK);
        g2d.setFont(new Font("宋体",Font.BOLD,18));//a 4 3 r
        String words = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        int x = 10;
        for(int i=0;i<4;i++){
            int idx = random.nextInt(words.length());
            // 获得指定位置的字符
            char ch = words.charAt(idx);
            // 旋转的角度  -30 到 30 之间
            int jiaodu = random.nextInt(60) - 30;
            // 将角度转化成弧度:
            double theta = jiaodu * Math.PI / 180;
            g2d.rotate(theta, x, 20);
            g2d.drawString(String.valueOf(ch), x, 20);
            g2d.rotate(-theta, x, 20);
            x+=30;
        }
        // 步骤四:将内存中的图片,进行输出
        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

升级版

package com.imooc.web.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 生成验证码图片
 */
@WebServlet("/CheckImgServlet")
public class CheckImgServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        int width = 120;
        int height = 30;

        // 步骤一 绘制一张内存中图片
        BufferedImage bufferedImage = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        // 步骤二 图片绘制背景颜色 ---通过绘图对象
        Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔
        // 绘制任何图形之前 都必须指定一个颜色
        graphics.setColor(getRandColor(200, 250));
        graphics.fillRect(0, 0, width, height);

        // 步骤三 绘制边框
        graphics.setColor(Color.WHITE);
        graphics.drawRect(0, 0, width - 1, height - 1);

        // 步骤四 四个随机数字
        Graphics2D graphics2d = (Graphics2D) graphics;
        // 设置输出字体
        graphics2d.setFont(new Font("宋体", Font.BOLD, 18));

        String words =
         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
        // String words = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
        Random random = new Random();// 生成随机数
        // 定义一个字符串,用于保存随机产生的四个字母或数字
        StringBuffer sb = new StringBuffer();
        // 定义x坐标
        int x = 10;
        for (int i = 0; i < 4; i++) {
            // 随机颜色
            graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random
                    .nextInt(110), 20 + random.nextInt(110)));
            // 旋转 -30 --- 30度
            int jiaodu = random.nextInt(60) - 30;
            // 换算弧度
            double theta = jiaodu * Math.PI / 180;

            // 生成一个随机数字
            int index = random.nextInt(words.length()); // 生成随机数 0 到 length - 1
            // 获得字母数字
            char c = words.charAt(index);
            // 将产生字符存入到StringBuffer中
            sb.append(c);
            // 将c 输出到图片
            graphics2d.rotate(theta, x, 20);
            graphics2d.drawString(String.valueOf(c), x, 20);
            graphics2d.rotate(-theta, x, 20);
            x += 30;
        }
        // 将产生的字符串存入到session中:
        request.getSession().setAttribute("checkCode", sb.toString());

        // 步骤五 绘制干扰线
        graphics.setColor(getRandColor(160, 200));
        int x1;
        int x2;
        int y1;
        int y2;
        for (int i = 0; i < 30; i++) {
            x1 = random.nextInt(width);
            x2 = random.nextInt(12);
            y1 = random.nextInt(height);
            y2 = random.nextInt(12);
            graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
        }
        // 将上面图片输出到浏览器 ImageIO
        graphics.dispose();// 释放资源
        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
    /**
     * 取其某一范围的color
     * 
     * @param fc
     *            int 范围参数1
     * @param bc
     *            int 范围参数2
     * @return Color
     */
    private Color getRandColor(int fc, int bc) {
        // 取其随机颜色
        Random random = new Random();
        if (fc > 255) {
            fc = 255;
        }
        if (bc > 255) {
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

}

看不清,换一张

<script type="text/javascript">
    function changeImg(){
        var codeImg = document.getElementById("codeImg");
        codeImg.src="${pageContext.request.contextPath }/CheckImgServlet?time="+new Date().getTime();/*保证每次获访问的URL不同*/
    }
</script>

验证码校验

// 完成验证码的校验:
    // 获得session中保存的验证码的信息
    String code1 = (String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
    // 接收前台表单提交的验证码的信息
    String code2 = request.getParameter("checkCode");
    if(code2==null || !code2.equalsIgnoreCase(code1)){
        request.setAttribute("msg", "验证码输入不正确!");
        request.getRequestDispatcher("/login.jsp").forward(request, response);
        return;
    }

Kaptck验证码

配置

 <servlet>
    <servlet-name>KaptchaServlet</servlet-name>
    <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
 </servlet>
 <servlet-mapping>
    <servlet-name>KaptchaServlet</servlet-name>
    <url-pattern>/KaptchaServlet</url-pattern>
 </servlet-mapping>
 ```
## jsp
```jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="" method="post">
        验证码:<input type="text" name="checkcode"/>
        <img id="codeImg" onclick="changeImg()" src="${pageContext.request.contextPath }/KaptchaServlet"><br/>
        <input type="submit" value="提交">
    </form>
</body>
</html>

看不清换一张

<script type="text/javascript">
    function changeImg(){
        var codeImg = document.getElementById("codeImg");
        codeImg.src="${pageContext.request.contextPath }/KaptchaServlet?time="+new Date().getTime();/*保证每次获访问的URL不同*/
    }
</script>

属性配置

 <servlet>
    <servlet-name>KaptchaServlet</servlet-name>
    <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
    <!-- 修改随机的字母或数字的长度 -->
    <init-param>
        <param-name>kaptcha.textproducer.char.length</param-name>
        <param-value>4</param-value>
    </init-param>
    <!-- 修改字体大小 -->
    <init-param>
        <param-name>kaptcha.textproducer.font.size</param-name>
        <param-value>25</param-value>
    </init-param>
    <!-- 修改字体空隙 -->
    <init-param>
        <param-name>kaptcha.textproducer.char.space</param-name>
        <param-value>10</param-value>
    </init-param>
    <!-- 修改图片的宽高 -->
    <init-param>
        <param-name>kaptcha.image.width</param-name>
        <param-value>120</param-value>
    </init-param>
    <init-param>
        <param-name>kaptcha.image.height</param-name>
        <param-value>30</param-value>
    </init-param>
 </servlet>
 <servlet-mapping>
    <servlet-name>KaptchaServlet</servlet-name>
    <url-pattern>/KaptchaServlet</url-pattern>
 </servlet-mapping>

验证码校验

// 完成验证码的校验:
        // 获得session中保存的验证码的信息
        String code1 = (String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
        // 接收前台表单提交的验证码的信息
        String code2 = request.getParameter("checkCode");
        if(code2==null || !code2.equalsIgnoreCase(code1)){
            request.setAttribute("msg", "验证码输入不正确!");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
            return;
        }
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